Sewing machine adjustable eccentric mechanism



July 14, 1959 J. P. PAJOR 2,894,471

SEWING MACHINE ADJUSTABLE ECCENTRIC MECHANISM Filed Au 16, 1957 s Sheets-Sheeti FIG.|

Jul 14, 1959 J. P. PAJOR 2,894,471

SEWING MACHINE ADJUSTABLE ECCENTRIC MECHANISM Filed Aug. 16, 1957 5 Sheets-Sheet 2 FIG.2

y 1959 J. P. PAJOR I 2,894,471

sswmc MACHINE ADJUSTABLE ECCENTRIC MECHANISM Filed Aug. 16, 1957 v 5 Sheets-Sheet :s

. J. P. PAJOR July 14, 1959 SEWING MACHINE ADJUSTABLE ECCENTRIC MECHANISM File d Aug. 16, 1957 5 Sheets-Sheet 4 July 14, 1959 PQPAJOR 2,894,471

SEWING MACHINE ADJUSTABLE ECCENTRIC MECHANISM Filed Aug. 16, 1957 5 Sheets-Sheet 5 FIG. l0

United Sttes Patent MACHINE ADJUSTABLE ECCENTRIC MECHANISM Joseph P. PajoQChicago, lllr, assignor to Union Special Machine Company, Chicago, 111., a corporation 'of Illinois Application August 16, 1957, Serial No. 678,640

Claims. (Cl. 112-209) The invention relates to sewing machines and more particularly to such machines provided with eccentrics for driving certain parts through a desired stroke or extent of movement upon each revolution of the eccentric, such stroke being variable from time to time, depending upon the nature of the work being performed. This applies especially to the work feeding devices of such machines which control the stitch length. It frequently becomes desirable to change the stitch length in the use of a machine on different types of work.

An object of the invention has been to provide a simple, compact and reliable mechanism capable of imparting a variable stroke or movement to a feed bar or the like and one which may be readily and quickly adjusted to vary the feed stroke of the bar, and hence the stitch length of the machine. The improved construction in accordance with the invention is such that a small and lightweight adjustable eccentric is provided. This, in. addition to meeting the small space limitations of Icertairi machines, reduces inertia forces to a minimum and thusmakes possible quick starting and stopping and high speed operation of the sewing machine.

A special purpose of the invention has been to provide an adjustable eccentric of the character indicated which especially is adapted for use in overedge sewing machines of the type having two closely adjacent feed bars arranged for four-motion movement, one feed bar carrying a main feed dog and the other a differential feed'dog. In such machines, as heretofore constructed, it has been customary to replace the eccentrics provided on the main shaft, for imparting feed and return movements to the feed bars, by eccentrics of different throw whenever it has been desired to vary the stitch length or the relative movements of the two feed bars. This has necessitated the maintenance of a stock of eccentrics of'the various different throws desired for the different types of work to be performed on the machines, and a certain time delay has been involved in substituting eccentrics. Some machines of this character have been provided with special linkages between the eccentrics and the feed bars by which the stroke of at least one of the feed bars may be varied in the use of eccentrics of constant throw. Such mechanisms have, however, been complicated and have required the provision of mechanisms which take up an excessive amount of space and involve parts which add inertia forces to the system.

In accordance with the present invention an adjustable eccentric is provided which requires little or no extra space and introduces no extra inertia forces beyond those characteristic of a machine having fixed ecc'e'n'tric's for driving the feed bars. The arrangement is such that the means for varying the throw of the eccentrics is confined within the space required by the eccentrics themselves and no extra weight is involved in the system of moving parts. In the preferred form or the invention, to achieve the specified results, each eccentric embodied in the mechanism is provided with an elongated central opening adapted to cooperate with "ice flat surfaces on the drive shaft and is retained in its desired position of adjustment by a single screw of predetermined length coinciding with the length of the opening, this screw being adjustable through a radial opening in the wall of the eccentric itself to vary the throw of the latter. Openings have also been provided in the straps cooperating with the eccentrics to facilitate adjustment of the latter and make unnecessary the removal and replacement of parts.

Other objects, features and advantages of the invention will appear from the detailed description of an illustrative embodiment of the same which will now be given in conjunction with the accompanying drawings, in which:

Fig. 1 is a plan view of a portion of the work supporting portion of a sewing machine embodying the invention, the cloth plate being omitted to show the parts beneath it;

Fig. 2 is a side elevational view of the portion of the machine shown in Fig. 1, as seen from the bottom thereof, portions being broken away and a part shown in section;

Fig. 3 is an axial sectionalview along the main drive shaft of the machine in the region thereof shown in Fig. 1;

Fig. 4 is a detail view in elevation of an adjustable eccentric and pitman used to drive a main feed bar;

Fig. 5 is a longitudinal sectional view through the pitman taken along the line 5-5 of Fig. 3;

Fig. 6 is a vertical sectional view through certain parts, taken along the line 6--6 of Fig. 2;

Fig. 7 is a vertical sectional view taken along the line 77 of Fig. 2;

Fig. 8 is a side elevational view of the main feed bar with its feed dogs;

Fig. 9 is a side elevational view of'the differential feed bar with its feed dog; I

Fig. 10 is a plan View of a throat plate embodied in the work supporting surface of the machine and shows the feed dogs in relation thereto; and

Fig. 11 is an exploded perspective view of the inner or left end of the main drive shaft of the machine and the various parts of the adjustable eccentrics for driving the main and'differential feed bars.

The invention has been illustrated as applied to an overedge sewing machine of the character disclosed in the patent to Wallenberg, et al. No. 2,704,042, granted March 15, 1955. Reference may be had to said patent for an understanding of suitable stitch forming devices and their operating means, and also edge trimming mechanism and its operating means which may be incorporated in the machine. The present description will be confined to the feed mechanism and the novel adjustable eccentric means for driving the latter.

As shown, the machine is provided with a main frame 10 of suitable form and construction in which is journaled a longitudinally extending drive shaft 11 which, it will be understood, carries a hand Wheel and pulley at its outer end through which power may be supplied for the operation of the machine. Shaft 11 is journaled in suitable bearings, such as the sleeve 12 (Fig. 3) and additional bearing sleeves at other points along its length. A main feed bar 13 and a differential feed bar 14 are mounted in side-by-side relationship and are arranged to be given four-motion movements to bring about the feeding of the work. At their rearward ends, as shown at the left in Figs. 8 and 9, the feed bars are forked to straddle and be guided upon 'a block 15 carried by an eccentric portion of a stud or rod 16. This stud is mounted in a suitable opening in the frame of the machine and has a screw driver receiving slot in its outer end to permit it to :be turned to vary slightly the elevation of the eccentric portion which carries the block 15. A set screw 17 serves to retain the stud 16 in set position. Adjacent its forward end the main feed bar 13 has a downwardly and forwardly extending portion 13a providing a forked formation with the main body of the bar presenting top and bottom flat surfaces arranged to' cooperate with a block 18 carried by an eccentric portion 19 of the shaft 11. Similarly, the feed bar 14 is provided with a downwardly and forwardly extending portion 14a to produce a forked formation arranged to straddle and slide upon the block 18. The arrangement is such that upon rotation of the shaft 11 the two feed bars will be lifted and lowered at their forward ends to impart lifting and lowering movements to the feed dogs which they carry. Such up and down movements of the feed bars are permitted by the pivotal action at their rearward ends about the axis of the eccentric portion of the stud 16. Outwardly of the eccentric portion 19 of shaft 11 the latter is provided with a further eccentric portion 20 having flat surfaces 21, 21 at opposite sides thereof and interconnecting arcuate or partially cylindrical surfaces. On the portion 20 of shaft 11 is mounted an eccentric element 22 having a central opening which is elongated in a direction transversely of the axis of the shaft. This opening presents flat surfaces 22a arranged to cooperate with the surfaces 21 and have a relatively snug, sliding fit in relation thereto. The top and bottom surfaces of the opening, as shown in Fig. 11, are preferably of armate or partially cylindrical form as indicated at 22b. Also mounted on the portion 20 of shaft 11 is another eccentric 23 similar to eccentric 22. It has a central opening providing flat surfaces 23a arranged to cooperate with the surfaces 21 and providing arcuate or partially cylindrical surfaces 23b at the top and bottom of the opening. A screw 24 having screw threaded engagement with the portion 20 of the shaft has a length substantially coinciding with the height of the opening through the eccentric element 22. The top and bottom surfaces 22b of the latter have a relatively snug fit in relation to the head and tip of the screw. By turning the screw 24, the position of the element 22 in relation to portion 20 may be adjusted and thus vary the eccentricity of the outer surface of element 22 in relation to the axis of shaft 11. An opening 220 is provided through the wall of the element 22 to permit the insertion of the tip of a relatively small screw driver into cooperation with the head of the screw 24 to effect the adjustment of eccentricity of element 22. Similarly, element 23 cooperates with a screw 25 having screw threaded engagement with portion 20 of shaft 11. The head and tip of this screw cooperate with the opposed surfaces 23b. A screw driver may be inserted through an opening 230 in the wall of the element 23 to enable turning of the screw 25 to adjust the eccentricity of element 23 in relation to the axis of shaft 11. As shown in Figs. 3 and 5, the heads of the screws 24 and 25 are somewhat larger in diameter than the openings 22c and 230. A washer 26 is interposed between a shoulder 19a provided at the end of portion 19 of shaft 11 and the adjacent wall of the element 23. Similarly, a washer 27 is interposed between the opposed faces of the eccentric elements 22 and 23. In assembling the various parts described on the portion 20 of shaft 11 the screws 24 and 25 are first removed. The washer 26 is then applied and the screw 25 inserted. Element 23 is then applied and washer 27 introduced next to this. The screw 24 is then inserted and element 22 applied. The various parts are held in tightly assembled relation on the portion 20 by means of a nut 29 cooperating with a threaded extension 28 at the end of shaft 11. The arrangement is such that a flanged portion 29a of the nut is brought firmly against the outer face of the element 22 to squeeze together all of the parts mentioned and to force the washer 26 firmly against "the face 19a. Flange 29a does not quite engage the outer end of portion 20 of shaft 11. In this way the various parts mentioned are clamped for rotation with the shaft 11. The cooperation of the flat surfaces on the portion 20 of the shaft and on the eccentric elements 22. and 23 further insures rotation of these parts in unison.

Cooperating with the eccentric 22 is a strap portion of a pitman 30 (Figs. 2-6) which serves to transmit motion to the main feed bar 13. For this purpose, as best shown in Fig. 6, the pitman has an opening therethrough adjacent its reduced rearward end cooperating with a sleeve 31 carried by a bolt 32. The latter has an enlarged head 32a provided with a screw driver receiving slot and fitted into a recess in the inner face of the feed bar 13. A nut 33 serves to retain the sleeve 31 and bolt 32 in assembled relation on the feed bar and allows rocking movement of the pitman 30'relative to the sleeve 31. As shown in Figs. 3 and 5, the strap portion of pitman 30 is provided with an opening 30a which may be aligned with the opening 220 in element 22 when the shaft 11 is turned into proper position. This enables the insertion of the screw driver mentioned above for adjusting the screw 24.

A pitman 34, similar to pitman 30 but of somewhat greater length, has a strap portion cooperating with the element 23 and has its opposite end connected with the feed bar 14. The latter connection is best shown in Fig. 7 and involves a bolt passing through a sleeve 34!; cooperating with an opening in the reduced end portion of the pitman 34. Bolt 35 has an enlarged head 35:: provided with a screw driver receiving slot, this head fitting into a recess in the inner wall of the feed bar 14. A nut 36 cooperating with the bolt 35 serves to retain the sleeve 34b and the feed bar in assembled relation while the pitman 34 is permitted to rock about the sleeve 34b. As will be seen in Figs. 2 and 7, the sleeve 34b passes beneath the main body of the feed bar 13 whose downward extension occurs toward the right of this point (Fig. 2). Pitman 34 is provided with an enlarged opening 340 in the region through which the sleeve 31 is passed (see Figs. 2 and 6).

Feed bar 13 is arranged to carry the main feed dog and a chaining feed dog, the latter cooperating with the free chain produced when no work is present at the stitch forming position. As shown in Fig. 2, feed bar 13 is provided with a vertically extending channel 37 and a screw threaded opening 38 adapted to receive a screw 39 (Fig. 8) which cooperates with a vertically elongated opening 40 in the shank of a main feed dog 41. Opening 40 permits slight vertical adjustment of the feed dog in relation to the feed bar. An elongated opening 42 in the feed bar is arranged to receive the shank of a screw 43 having screw threaded engagement with an opening through the shank of a chaining feed dog 44. This arrangement is also such that the chaining feed dog is subject to slight vertical adjustment in relation to the feed bar 13. Feed bar 14 is provided with a vertically disposed channel 45 and a threaded opening 46 arranged to receive a screw 47 having threaded engagement with the opening 46. Screw 47 passes through an elongated opening 48a in the shank of a differential feed dog 48, the arrangement being such that the vertical position of the latter in relation to the feed bar 14 may be adjusted slightly.

The work supporting portion of the machine frame is provided with a throat plate 49 having suitable openings or cutaway portions permitting the feed dogs 41, 44 and 48 to move up and down and also longitudinally of the throat plate, in the course of receiving their four-motion movements. Throat plate 49 is provided with an opening 50 adapted to receive a screw by which it is secured to the frame of the machine.

It will be seen from the foregoing that a very simple and compact arrangement has been provided for adjusting the stroke of two eccentrics which impart feed and return movements to two closely adjacent feed dog carry ing bars. Moreover, the eccentrics cooperate with two closely adjacent pitmans which are in turn right alongside of the feed bars, thus providing a very compact assembly. The adjustment of these eccentrics may be readily effected by turning the shaft 11 until the screws 24 and 25 are in a predetermined angular position so that the openings 30a and 34a in the pitmans 3t and 34, respectively, are aligned with the openings 22!: and 23c in the elements 22 and 23, respectively. At this time the stem of a small screw driver may be readily inserted through the aligned openings mentioned and the screws 24 and 25 may be turned to produce the desired adjustment. Before effecting the adjustment the nut 29 should be backed off slightly to permit the desired movement of the eccentrics.

Also it will be noted that the eccentrics are no Wider than the portions thereof which cooperate with the straps of the pitmans, and the means for adjusting the eccentrics and retaining them in adjusted position are all within the confines of the eccentrics, in both radial and axial directions.

While the invention has special utility in relation to a feed mechanism of the character disclosed, involving a main and a differential feed bar in side-by-side relation, it Will be understood that the novel adjustable eccentric construction may be used in other types of sewing machines and in connection with other mechanisms the stroke or extent of movement of which, during each revolution of a drive shaft, should be made variable to enable the machine to perform operations on different types of work. Thus, a single adjustable eccentric of the form described may be used to drive a single feed bar or it may be used in the driving of an intermittently operable feed roller or the like.

Various changes may be made in the form and arrangement of the several parts of the combination disclosed without departing from the principles and scope of the invention as defined by the claims.

What is claimed is:

1. In a high speed sewing machine having a rotary drive shaft and means arranged to be driven thereby through different extents of movement, the combination which comprises an eccentric mounted on said shaft and arranged to be driven by said shaft, a pitman having a strap at one end thereof surrounding said eccentric and having its opposite end connected with said means, a single adjustable screw of predetermined length carried by said shaft within the axial confines of said eccentric and cooperating with said eccentric to retain the same in a definite position in relation to the axis of said shaft, said screw having threaded engagement with said shaft and having its ends cooperating with opposed surfaces on said eccentric which face inwardly toward the axis of said shaft and are spaced apart a distance equal to the length of said screw to retain the eccentric in adjusted position in relation to the axis of said shaft, and locking means for retaining said eccentric in adjusted position comprising means for exerting a friction-creating force thereon in a direction parallel with the axis of said eccentrio.

2. In a high speed sewing machine having a rotary drive shaft and means arranged to be driven thereby through different extents of movement, the combination which comprises an eccentric mounted on said shaft and arranged to be driven by said shaft, said eccentric and shaft having cooperating flat surfaces enabling diametral movement of said eccentric in relation to said shaft, a pitman having a strap portion surrounding said eccentric, means adjacent the opposite end of said strap for maintaining the same on said eccentric, a single adjustable screw within the dimensional limits of said strap c0 acting between said shaft and said eccentric for retaining the latter in predetermined, variable eccentric relation to said shaft, and locking means for retaining said eccentric in adjusted position comprising means for exerting a friction-creating force thereon in a direction parallel with the axis of said eccentric.

3. In a high speed sewing machine having a rotary drive shaft and a four-motion feed dog arranged to be driven thereby, the combination which comprises a feed bar mounted for up and down movements in a vertical plane and longitudinal movements in said plane, an eccentric on said shaft for imparting said up and down movements to said bar, and an adjustable eccentric on said shaft and connections therefrom for imparting longitudinal movements to said bar, said adjustable eccentric having a circular bearing surface and said connections having a strap surrounding said circular surface, said adjustable eccentric comprising an element mounted for diametral movement in relation to said shaft and having surfaces thereon cooperating with surfaces on said shaft for compelling rotation of said shaft and elementin unison, said element having an elongated opening therethrough enabling said diametral movement of said element in relation to said shaft, a single adjustable screw radially alined with said circular surface within the axial confines thereof and cooperating with said element and said shaft for retaining said element in predetermined relation to said shaft in a direction transverse to the axis thereof, and locking means for retaining said element in adjusted position comprising means for exerting a friction-creating force thereon in a direction parallel with the axis of said element.

4. In a high speed sewing machine having a rotary drive shaft, a plurality of feed bars in side-by-side relationship and a plurailty of pitmans in side-by-side rela tionship closely adjacent to said feed bars, the combination which comprises a plurality of eccentric elements in closely spaced relationship on said shaft, each of said eccentric elements cooperating with one of said pitmans and having its dimension axially of said shaft substantially equal to the thickness of said pitman, said eccentric elements each having an elongated, diametrally extending opening providing fiat surfaces for cooperation with flat surfaces on said shaft, a single adjustable screw extending radially of each of said eccentric elements within the axial confines thereof in line with the major axis of the elongated opening therein, each of said screws serving to retain its related eccentric element in predetermined eccentric relationship to the axis of said shaft and being turnable to vary said eccentricrelationship, and locking means for retaining said eccentrics in adjusted position comprising means for exerting a friction-creating force on said eccentric parallel with the axis thereof.

5. In a machine of the character set forth in claim 4, each of said pitmans having a strap portion surrounding a related eccentric element, each of said screws having a slotted head abutting an inwardly facing surface of the related eccentric, each of said strap portions having an opening therethrough adapted to be alined with said radial opening in the related eccentric element to enable the insertion of the tip of a screw driver for turning the related screw.

References Cited in the file of this patent UNITED STATES PATENTS 1,543,945 Moifat June 30, 1925 2,704,042 Wallenberg et a1. Mar. 15, 1955 FOREIGN PATENTS 515,585 Great Britain Dec. 8, 1939 

